Marcus Island LORAN-C transmitter

Marcus Island LORAN-C transmitter, or Minami Torishima LORAN-C transmitter, is a former LORAN-C transmitter on Minami-Tori-shima (Marcus Island) in Ogasawara, Tokyo, Japan at (24°17′8″N 153°58′54″E). Until 1993 it was part of Grid 9970 and used a transmission power of 4000 kilowatts, which was more than the most powerful broadcasting stations ever used.

Minami-Tori-shima (Marcus Island) overview with transmitter

Marcus Island LORAN-C Mast (1st)
General information
Status	Dismantled
Type	Mast radiator insulated against ground
Location	Minami-Tori-shima (Marcus Island), Japan
Completed	1963
Destroyed	1985
Height	411.48 m (1,350.0 ft)

Marcus Island LORAN-C Mast (2nd)
General information
Status	Dismantled
Type	Mast radiator insulated against ground
Location	Minami-Tori-shima (Marcus Island), Japan
Completed	1986
Destroyed	2000
Height	213.4 m (700 ft)

Marcus Island LORAN-C Mast (3rd)
General information
Status	Dismantled
Type	Mast radiator insulated against ground
Location	Minami-Tori-shima (Marcus Island), Japan
Completed	2000
Destroyed	2010
Height	213 m (698.82 ft)
Design and construction
Main contractor	Japan Self-Defense Forces

Until 1985 Marcus Island LORAN-C transmitter had a 411.48-meter (1,350.0 ft) tall guyed mast radiator as an antenna, which was built in 1964. In 1985/86 the 411.48-metre tower was replaced by a 213.4 m-tall (700 ft) tall tower.

In October 1993 the authority over the transmitter was transferred from the United States Coast Guard to the Japan Coast Guard. In 2000 the tower of the station was again dismantled and replaced by a new one with a height of 213 meters.

Marcus Island LORAN-C transmitter was the X-Ray secondary station of the North West Pacific LORAN-C Chain GRI 8930. Its transmission power was reduced to 1100 kilowatts.

On December 1, 2009, the station was abolished due to a decline in users.[1] The mast has been demolished.